Gates walked through the mile-long production facility, getting briefed at stops along the way and chatting with workers on the production line.

The Lockheed-Martin facility has been used since 1942 to build military aircraft. Today, the front fuselage and wings of the latest-generation combat aircraft are built here. Then, they’re incorporated, along with the center and aft fuselage pieces built by other contractors, into the final product.

“The importance of this aircraft cannot be overstated,” Gates told reporters, holding up the F-35 as an example of new, innovative and more cost-effective ways to meet the country’s current and future defense needs.

The F-35 is the first aircraft to be developed within the Defense Department to meet the needs of three services, with three variants being developed simultaneously. This brings cost savings and economies of scale not possible with separate aircraft, because the F-35s will share common components and maintenance requirements, Gates noted.

“We cannot afford as a nation not to have this airplane,” he said, noting that every dollar saved in acquisition frees up a dollar to support other critical wartime requirements.

The Air Force will receive the F-35’s “A” variant, which will provide conventional takeoff and landing capabilities. The Marine Corps is slated to receive the “B” variant that has a vertical-lift capability. The Navy will receive the “C” variant, designed for carrier launches.

The different F-35 variants will replace the legacy F-16 aircraft for the Air Force and the F/A-18 and AV-8 aircraft for the Navy and Marine Corps.

Gates said he was impressed by the investments made in the production line, with robotics and automation bringing speed and precision to the operation. Lockheed-Martin poured $1 billion into the facility to prepare it for F-35 production, officials said, and is adding another 250,000 feet of floor space to the more than 1 million square feet currently used.

But even more impressive, Gates said, is the “dedication and clear commitment of the men and women … working on this airplane.”

Gates said he’s particularly excited that the F-35 appears to be on schedule to equip the first training squadron at Eglin Air Force Base, Fla. , by 2011, and enable the Marine Corps to reach initial operational capability by 2012.

“So I am heartened by what I’ve seen here this morning,” he said, “but especially by the commitment of the people putting this airplane together.”

Marine Maj. Joseph Bachmann, an F-35 test pilot who goes by the call sign, “OD,” shares Gates’ enthusiasm about the aircraft he said will deliver a “quantum leap” in new capability.

“It’s important for him to see that this is a beautiful machine,” Bachmann said of Gates’ visit. “But I’d also like him to see that we are being good stewards with the taxpayers’ money, and working together to deliver on time.”

The Joint Strike Fighter will replace not only legacy U.S. aircraft, but also numerous aircraft for the international partners participating in the program.

During today’s tour, Gates walked beneath flags draped over the immaculate factory floor that reflect the broad partnership behind the F-35 program. Along with the Air Force, Navy and Marine Corps flags hung flags of the United States , United Kingdom , Italy , the Netherlands , Turkey , Canada , Denmark , Norway and Australia .

A huge banner at the entranceway to the plant captured the team spirit: “F-35 JSF: Where Our Future Comes Together.”

Gates credited that teamwork with overcoming challenges and moving forward with the program. The goal, he said is to complete the development program in the next few years, then move into full production.

At that point, the facility will ramp up from its current production of one aircraft per month to about one per day.

“We are in this position where we can deliver as promised,” said Jon Beesley, chief F-35 test pilot. “We’re developing things people have never done before and learning a lot of things along the way.”

Mike Bateman, an electrical installer who’s worked with the F-35 program for the past five years, said he’s proud of the way management listens to workers who are always trying to figure out ways to make the aircraft better and produce it faster.

Gates’ visit “is pretty awesome,” Bateman said. “He’s getting a chance to see the quality here, and the fact that we are going to make these schedules and under budget,” he said.

Steve Nelson, a Lockheed-Martin manager who supervises the forward fuselage operation, said he hoped Gates got a sense during his visit about what makes the F-35 such a distinctive program.

“I want him to take away how much the engineering has progressed, and how people are working together to get the fifth-generation aircraft out the door and to our country,” he said.